Reduction of Staphylococcus epidermidis adhesion to indwelling medical devices : a simple procedure

The present study aims to find a method to reduce Staphylococcus epidermidis adhesion to acrylic and silicone – two materials used commonly in medical devices – by heparin and gentian violet surface preconditioning. Different periods of heparin preconditioning are studied to evaluate the influence of preincubation time on the reduction of bacterial adhesion. A two-hour period was chosen and applied in the adhesion assays with either heparin or gentian violet. Squares of the materials with adherent cells were also analysed by scanning electron microscopy (SEM). Results of adhesion assays showed a significant reduction (53–90%, P0.05) were found between the extent of adhesion on silicone coupons precontacted either with heparin or gentian violet for each of the strains tested. On acrylic, heparin was more efficient (P<0.001) in reducing S. epidermidis IE186 adhesion than was gentian violet (85% and 53% reductions, respectively). Therefore, immersion of acrylic and silicone in heparin or gentian violet may constitute a simple and effective method by which to reduce S. epidermidis adhesion to medical devices.Fundação para a Ciência e a Tecnologia (FCT) - projecto POCTI/ESP/42688/2001, SFRH/BD/19265/2004 and SFRH/BPD/26803/200

Relevance of cell wall and extracellular matrix proteins to Staphylococcus epidermidis adhesion and biofilm formation

In the present study, the protein profiles of the cell wall (CW) extracts of eight Staphylococcus epidermidis strains were analysed. The protein pattern of the extracellular matrix (EM) of four S. epidermidis good biofilm producer strains was also obtained. The main goal was to relate these protein patterns with their bacterial adhesion and biofilm forming ability. For this purpose, 2 h adhesion and 8 d-old biofilm assays were carried out, with the adhered cells and biomass quantified by microscopic observation and crystal violet quantification, respectively. CW and EM proteins were visualized by SDS-PAGE. According to the results, a significant percentage of the CW proteins detected was common to all the strains studied. However, the most adhering strains expressed a high number of proteins associated with the initial adhesion process, and the strongest biofilm producers expressed proteins that were absent in the protein profile of the strains that produced lower amounts of biofilm. Therefore, the present results demonstrate the importance of such proteins in adhesion and biofilm formation processes. Some of the CW proteins were also present in the EM protein pattern, though to a smaller amount, as well as several exoenzymes important for the host immune system invasiveness.Claudia Sousa and Pilar Teixeira acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT), through the grants SFRH/BD/19265/2004 and SFRH/BPD/26803/2006, respectively

When the Conception of Symmetry Deceives Us: A Case Report on the Perioperative Diagnosis of Subclavian Artery Stenosis

Subclavian artery stenosis is a relatively uncommon manifestation of peripheral artery disease with significant morbidity. We describe a case of left subclavian artery stenosis that became apparent in the intraoperative setting, in a patient who presented for emergency surgery after a fall and subsequent left femoral neck fracture. Initial non-invasive blood pressure readings on the left upper extremity were in the normal range but after placement of the arterial line on the right upper extremity, the discrepancy was evident pointing towards a structural abnormality as the causative factor. CT angiography was found to confirm the diagnosis of left subclavian artery stenosis of an atherosclerotic nature. A thorough physical examination can point to the presence of subclavian stenosis through pulse amplitude and blood pressure asymmetries. This study highlights the importance of obtaining blood pressure readings ideally on all four limbs to avoid misinterpretation of blood pressure values that could ultimately lead to the use of unnecessary and inadequate interventions and possible complications in the perioperative setting.info:eu-repo/semantics/publishedVersio

Metabolic activity of Staphylococcus epidermidis in biofilm versus planktonic cells

Staphylococcus epidermidis is at the moment one of the main responsible microorganisms for nosocomial infections due to the colonization of indwelling medical devices and its biofilm forming ability. The reason for that relies on the very low sensibility of biofilms to antibiotics when compared to planktonic cells, making them difficult to eradicate and a serious health problem. Thus, it is of utmost importance to understand and to identify the differences in the physiology and metabolic activity between planktonic and sessile cells in order to define adequate treatment strategies. The aim of this work was the comparison of the metabolic activity of biofilms formed by 6 strains of S. epidermidis among them and with the corresponding planktonic cells. The biofilm biomass and cell concentration were also quantified in order to determine its influence on cell activity and if these factors are strain dependent. Two reference strains (9142 and 9142-M10) and four clinical isolates (IE75, IE186, IE214 and LE7) were studied in this work. The biofilms were formed on acrylic squares of 2 cm x 2 cm, during eight days, in fed-batch mode. The total attached biomass was quantified by staining with crystal violet and the biofilm cell concentration was determined as CFU/ml. The metabolic activity of biofilms and cells in suspension from the same strains was evaluated through the measurement of glucose consumption along 60 minutes. The results revealed different abilities of biofilm formation among the different S. epidermidis strains, with strain 9142 demonstrating a significantly (p<0.05) greater capacity of biofilm formation in opposition with all the remaining five strains, especially 9142-M10, IE75 and LE7, the ones with the lowest values of biofilm biomass formation. This strain variability was also confirmed with the determination of biofilm cell concentration by CFU plating. These results also evidence, together with the biomass quantification results that besides cells, that part of the total biomass is composed of extracellular matrix that may differ according with the strain. As far as metabolic activity is concerned this study indicates that cells growing in biofilm are metabolically less active than free cells. In conclusion, this work helps to confirm the phenotypic variability of S. epidermidis strains and the different pattern of behaviour between sessile and free cells. When cells are adhered to a surface, such as acrylic, they become involved in a different environment – decreased nutrient and oxygen supply, for example - from that in suspension, and this appears to have a strong influence in cells activity, leading to a decreased metabolic rate and, as a consequence, to a decreased antimicrobial susceptibility

Obesity, energy balance and spermatogenesis

Obesity has grown to pandemic proportions. It affects an increasing number of children, adolescents and young adults exposed to the silent comorbidities of this disorder for a longer period. Infertility has arisen as one important comorbidity associated with the energy dysfunction promoted by obesity. Spermatogenesis is a highly regulated process that is determined by specific energetic requirements. The reproductive potential of males relies on hormonal-dependent and -independent stimuli that control sperm quality. There are conflicting data concerning the impact of male overweight and obesity on sperm quality, as well as on the possible paternal-induced epigenetic trait inheritance of obesity. In addition, it remains a matter of debate whether massive weight loss induced by lifestyle interventions, drugs or bariatric surgery may or may not benefit obese men seeking fatherhood. Herein, we propose to discuss how energy balance may modulate hormonal signalling and sperm quality in overweight and obese men. We also discuss some molecular mechanisms that mediate obesity-related dysfunction in male reproductive system and how paternal obesity may lead to trait inheritance. Finally, we will discuss how lifestyle modifications and sustained weight loss, particularly the loss achieved by bariatric surgery, may revert some of the deleterious effects of obesity in men and their offspring.info:eu-repo/semantics/publishedVersio

The role of Cu length on the magnetic behaviour of Fe/Cu multi-segmented nanowires

CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOA set of multi-segmented Fe/Cu nanowires were synthesized by a two-step anodization process of aluminum substrates and a pulsed electrodeposition technique using a single bath. While both Fe segment length and diameter were kept constant to (30 +/- 7) and (45 +/- 5) nm, respectively, Cu length was varied between (15 +/- 5) and (120 +/- 10) nm. The influence of the non-magnetic layer thickness variation on the nanowire magnetic properties was investigated through first-order reversal curve (FORC) measurements and micromagnetic simulations. Our analysis confirmed that, in the multi-segmented Fe/Cu nanowires with shorter Cu segments, the dipolar coupling between Fe segments controls the nanowire magnetic behavior, and its performance is like that of a homogenous Fe nanowire array of similar dimensions. On the other hand, multi-segmented Fe/Cu nanowires with larger Cu segments act like a collection of non-interacting magnetic entities (along the nanowire axis), and their global behavior is mainly controlled by the neighbor-to-neighbor nanodisc dipolar interactions.87112CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO234513/2014-4sem informaçãoAgências de fomento estrangeiras apoiaram essa pesquisa, mais informações acesse artig

New Quantum-Dot-Based Fluorescent Immunosensor for Cancer Biomarker Detection

Cancer antigen 15-3 (CA 15-3) is a biomarker for breast cancer used to monitor response to treatments and disease recurrence. The present work demonstrates the preparation and application of a fluorescent biosensor for ultrasensitive detection of the cancer antigen CA 15-3 protein tumor marker using mercaptopropionic-acid-functionalized cadmium telluride (CdTe@MPA) quantum dots (QDs) conjugated with CA 15-3 antibodies. First, the QDs were synthesized by the hydrothermal route, resulting in spherical nanoparticles up to 3.50 nm in diameter. Subsequently, the QD conjugates were characterized by Fourier transform infrared spectroscopy (FTIR), UV absorption, and fluorescence. The interaction between the conjugates and the protein was studied by fluorescence spectroscopy in buffer and in 10-fold diluted commercial human serum. Calibration in spiked serum samples gave a detection limit of 0.027 U/mL, 1000-fold lower than the clinical limit for CA 15-3 (25 U/mL to 30 U/mL), indicating that this is an ultrasensitive technique. In addition, a rapid response was obtained within 10 min. The biosensor was selective in the presence of the interfering serum proteins BSA, CEA, and CA-125, with a maximum interference of 2% for BSA. The percent recovery was close to 100% with maximum relative standard deviation (RSD%) values of 1.56. Overall, the developed CA 15-3 biosensor provides a simple and sensitive method for ultrasensitive monitoring of breast cancer, as well as the ability to detect other molecules of interest in human serum matrices.This research was funded by Fundação para a Ciência e Tecnologia, I.P, grant number 2022.09032.PTDCinfo:eu-repo/semantics/publishedVersio

Human phenylalanine hydroxylase as the case study

Funding Information: Authors acknowledge Sofarimex, Indústria Química e Farmacêutica SA, Portugal, for all the support concerning freeze-drying studies. This work was supported by FEDER and Fundação para a Ciência e a Tecnologia, I. P. through iMED.ULisboa (Projects UIDB/04138/2020 and UIDP/04138/2020), iNOVA4Health (UIDB/04462/2020, UIDP/04462/2020) and LS4FUTURE Associated Laboratory (LA/P/0087/2020) and research project PTDC/EBB-BIO/101237/2008 and research grant SFRH/BD/47946/2008 (to Paulo R. Lino). This work has also received funding from the National PKU Alliance, USA. The authors would like to thank Luís Miguel Ramos and Cátia Nascimento who contributed to the exploratory research that culminated in the work herein presented. Funding Information: Authors acknowledge Sofarimex, Indústria Química e Farmacêutica SA, Portugal, for all the support concerning freeze-drying studies. This work was supported by FEDER and Fundação para a Ciência e a Tecnologia, I. P. through iMED.ULisboa (Projects UIDB/04138/2020 and UIDP/04138/2020), iNOVA4Health (UIDB/04462/2020, UIDP/04462/2020) and LS4FUTURE Associated Laboratory (LA/P/0087/2020) and research project PTDC/EBB-BIO/101237/2008 and research grant SFRH/BD/47946/2008 (to Paulo R. Lino). This work has also received funding from the National PKU Alliance, USA. Publisher Copyright: © 2023 The Author(s)The structural maintenance of therapeutic proteins during formulation and/or storage is a critical aspect, particularly for multi-domain and/or multimeric proteins which usually exhibit intrinsic structural dynamics leading to aggregation with concomitant loss-of-function. Protein freeze-drying is a widely used technique to preserve protein structure and function during storage. To minimize chemical/physical stresses occurring during this process, protein stabilizers are usually included, their effect being strongly dependent on the target protein. Therefore, they should be screened for on a time-consuming case-by-case basis. Herein, differential scanning fluorimetry (DSF) and isothermal denaturation fluorimetry (ITDF) were employed to screen, among different classes of freeze-drying additives, for the most effective stabilizer of the model protein human phenylalanine hydroxylase (hPAH). Correlation studies among retrieved DSF and ITDF parameters with recovered enzyme amount and activity indicated ITDF as the most appropriate screening method. Biochemical and biophysical characterization of hPAH freeze-dried with ITDF-selected stabilizers and a long-term storage study (12 months, 5 ± 3 °C) showed that the selected compounds prevented protein aggregation and preserved hPAH structural and functional properties throughout time storage. Our results provide a solid basis towards the choice of ITDF as a high-throughput screening step for the identification of protein freeze-drying protectors.publishersversionpublishe

Metabolic dynamics of human Sertoli cells are differentially modulated by physiological and pharmacological concentrations of GLP-1

Obesity incidence has pandemic proportions and is expected to increase even further. Glucagon-like peptide-1 (GLP-1) based therapies are well-established pharmacological resources for obesity treatment. GLP-1 regulates energy and glucose homeostasis, which are also crucial for spermatogenesis. Herein, we studied the GLP-1 effects in human Sertoli cells (hSCs) metabolism and mitochondrial function. hSCs were cultured in absence or exposed to increasing doses of GLP-1 mimicking physiological post-prandial (0.01 nM) levels or equivalent to pharmacological levels (1 and 100 nM) used for obesity treatment. We identified GLP-1 receptor in hSCs. Consumption/production of extracellular metabolites were assessed, as well as protein levels or activities of glycolysis-related enzymes and transporters. Mitochondrial membrane potential and oxidative damage were evaluated. Glucose consumption decreased, while lactate production increased in hSCs exposed to 0.01 and 1 nM GLP-1. Though lactate dehydrogenase (LDH) protein decreased after exposure to 100 nM GLP-1 its activity increased in hSCs exposed to the same concentration of GLP-1. Mitochondrial membrane potential decreased in hSCs exposed to 100 nM of GLP-1, while formation of carbonyl groups was decreased in those cells. Those effects were followed by an increase in p-mammalian target of rapamycin (mTOR) Ser(2448). Overall, the lowest concentrations of GLP-1 increased the efficiency of glucose conversion to lactate, while GLP-1 concentration of 100 nM induces mTOR phosphorylation, decreases mitochondrial membrane potential and oxidative damage. GLP-1 regulates testicular energy homeostasis and pharmacological use of GLP-1 analogues could be valuable to counteract the negative impact of obesity in male reproductive function.info:eu-repo/semantics/publishedVersio